Field of the Invention—The present invention relates generally to pressure-sensitive adhesives and their application to desired surfaces, and more specifically to a mechanical handheld adhesive segment applicator apparatus for use in combination with rolls of indexed carrier release tape having pressure-sensitive adhesive segments attached thereto which may be individually dispensed using the mechanical handheld adhesive segment applicator apparatus.
Adhesives are more than just substances serving to hold materials together by surface attachment. The term “adhesive” is simplistic and explains little, but generically describes a class of “sticky” materials. Adhesives and adhesive applicators owe their innovation to the Industrial Revolution, which resulted in an explosion of technical and scientific breakthroughs. The breakthroughs of the Industrial Revolution included the introduction of new materials and ingredients for use in formulating market-specific and industry-specific adhesives. In creating novel adhesives, companies have diligently considered desirable qualities such as adhesive flexibility, toughness, minimum curing or setting time, and temperature and chemical resistance. Today, the technology and underlying science of adhesives and apparatuses for their application is the foundation for a multi-billion dollar industry with over 700 companies competing for market share. More importantly, these companies strive to create and introduce novel adhesives as well as apparatuses and methods for the simple, efficient, inexpensive, and safe application of adhesives.
One of the most significant adhesive technical breakthroughs of the past century has been the introduction of pressure-sensitive thermoplastic adhesives. Thermoplastic adhesives have excellent adhering qualities; they can be softened by heating and firmed by cooling. These characteristics help thermoplastic adhesives produce waterproof, resilient, and long-lasting flexible bonds. Thermoplastic adhesives have what is known as a “plastic memory,” meaning that each time a thermoplastic adhesive is heated, it can be molded into any desired form.
Thermoplastic adhesives have significant applications in today's industry. For example, in the preparation of mass mailings, marketers often desire to attach a card, such as a credit card or the like, to a carrier document so that a consumer can peel the card easily from the carrier document. One method of making such an attachment involves the use of a pressure-sensitive, thermoplastic adhesive. For example, by using a heating container to melt thermoplastic adhesive and a metering pump to dispense it during the printing or collating process, a portion of thermoplastic adhesive can be metered onto the carrier document and the credit card pressed against it.
In addition to the uses for thermoplastic adhesives described above, industry is now finding additional uses for them. For example, thermoplastic adhesives are routinely used and applied as small bond points to eliminate the use of mechanical fasteners, such as staples, screws, rivets, clips, snaps, nails, and stitching. Thermoplastic adhesives are also extensively used in the packaging and manufacture of cartons, boxes and corrugated boards, bags, envelopes, disposable products (diapers and other paper products), cigarettes, labels, and stamps. In fact, today's demand for thermoplastic adhesives extends to very broad fields of use and is not limited to assembly line-like settings.
Increasingly, industry demands thermoplastic adhesive application at on-site locations from portable, simple-to-use, efficient, inexpensive, and safe dispensing apparatuses. Additionally, such dispensing apparatuses must be able to adhere thermoplastic adhesives to non-planar, recessed, difficult to reach, or unstable surfaces. Previously known apparatuses and methods have failed to provide an adequate portable, simple-to-use, efficient, inexpensive, and safe dispensing device and a thermoplastic adhesive carrying medium capable of applying thermoplastic adhesives to non-planar, recessed, difficult to reach, or unstable surfaces.
In providing thermoplastic adhesives for application to a surface, the previously known embodiments have contemplated all of the following thermoplastic adhesive carrying media and application methods: hot-melt “glue-gun” adhesive dispensers; adhesive segment-laden carrier release tape for “by hand” adhesive application; use of a plunger-like dispensing system in combination with adhesive segment-laden carrier release tape, which proves to be cumbersome and which has a limited utility of application to planar surfaces; use of a cardboard box applicator system for use in combination with adhesive segment-laden carrier release tape, which is also limited in application to planar, non-recessed surfaces; and an electric automated dispensing system for use with adhesive segment-laden carrier release tape, which is activated by the pressing of a palm-sized push button, and which also only allows for application of thermoplastic adhesives to unobstructed planar surfaces.
Using a “glue gun” device is an inefficient, difficult, and at times unsafe method of applying thermoplastic adhesives to a desired surface. First, the cost of using this equipment is relatively high. The apparatus and method are also inefficient consumers of both energy and glue. Specifically, the costs of the activation of such a dispenser (electrical usage, wasted glue from droppings) for only short periods of time outweigh any other potential advantages which may be realized.
Safety is also an issue. Glue-gun devices are potentially unsafe because they include a heat source to heat a quantifiable supply of adhesive material to its melting point. A major drawback of using such an instrument is that the hot, molten thermoplastic adhesive can burn untrained users, and can also melt the substrate the user is applying the glue to. Finally, application of thermoplastic adhesives from a glue-gun does not enable the thermoplastic adhesive to withstand cold temperatures or to cool to a smooth surface, but instead will typically leave “spider webs” in the dried adhesive. In short, glue-gun applicators of the prior art are inefficient, difficult, and unsafe.
Many of the shortcomings of the glue-gun instruments of the prior art were solved by U.S. Pat. No. 5,935,670 to Downs (the “'670 Patent”), which patent is hereby incorporated herein by reference. However, upon further use of the technology of the '670 Patent, several shortcomings have become apparent. Specifically, while the '670 Patent discloses a method for presenting cooled adhesive segments for application to a desired surface, the application of the segments to the surface proves to be very inefficient.
The technology of the '670 Patent focuses mainly on the manufacture of a clean, unaltered carrier release tape having first and second release surfaces with different coefficients of friction, and the application thereto of adhesive segments at periodic intervals. The adhesive segment-laden carrier release tape is then wound into a roll. This embodiment allows a user to apply the adhesive segments from the carrier release tape by hand. Although such an embodiment provides a highly innovative and commercially successful product, application of the adhesive segments remains inefficient and cumbersome.
Specifically, the coiled adhesive segment-laden carrier release tape must be unrolled to present a adhesive segment for application. After the adhesive segment has been applied to the desired surface, the tape must be unrolled an additional distance to ready the next adhesive segment for application. Such a method is time-consuming, and the “spent” carrier release tape must be either torn off and disposed of or left intact and in the way. Finally, dropping or uncoiling the unused roll of adhesive segment-laden carrier release tape has also been a problem.
U.S. Pat. No. 6,319,442 to Downs (the “'442 Patent”), which patent is hereby incorporated herein by reference, further evolved the previously known adhesive segment-laden carrier release tape of the '670 Patent. Like the '670 Patent, the '442 Patent also contemplates a carrier release tape, which has first and second release surfaces with different coefficients of friction, and the application thereto of adhesive segments at periodic intervals. But unlike the '670 Patent, the '442 Patent contemplates a thermoplastic adhesive carrier release tape having a transverse line of slits or perforations precut across its transverse width and between the adhesive segments.
The precut tape of the '670 Patent thus allows individual portions of the carrier release tape and associated thermoplastic adhesive to be removed from the roll for manual application to a desired surface. While such an embodiment remedies the '670 Patent's problem of having a length of uncut spent carrier release tape, the carrier release tape of the '442 Patent (as well as of the '670 Patent) does not lend itself to use in combination with a more efficient dispenser for application of the adhesive segments to non-planar, recessed, difficult to reach, or unstable surfaces.
While the '670 and '442 Patents focus primarily on the creation of adhesive segment-laden carrier release tape, they also contemplate use of the adhesive segment-laden carrier release tape in combination with numerous dispenser apparatuses. First, a plunger-like applicator, as detailed within both the '670 and '442 Patents, proves manageable, but is limited in the type of surfaces that the thermoplastic adhesive may be applied to. Specifically, because the plunger mechanism has an attached planar foot portion, which is used to guide the placement of the adhesive segments, application of the thermoplastic adhesive segments is essentially confined to an unobstructed flat surface. Such a limitation can pose significant problems when attempting to apply thermoplastic adhesives to non-flat surfaces. It may be more practical to use the above “by hand” manual method of thermoplastic adhesive application.
Another previously known thermoplastic adhesive applicator that presents some apparent problems is the so-called box applicator. This applicator is also limited in thermoplastic adhesive application to planar surfaces. The box applicator encases a roll of adhesive segment-laden carrier release tape as disclosed within the '670 and '442 Patents. When the carrier release tape is advanced from the box applicator by hand, the thermoplastic adhesive can only be applied to surfaces that are of a generally planar nature.
The adhesive segments must be pressed between the surface to be glued and the top of the cardboard box applicator to ensure adherence. This application process exposes unspent adhesive segments to dust and other debris, which may cause the adhesive segments to lose their adhesive tack and damage or soil the desired surface. Additionally, because the cardboard box thermoplastic adhesive applicator must be of a certain size to house a spool of carrier release tape, application of adhesive segments to areas that are non-flat or recessed proves to be difficult, if not impossible.
While not all previously known thermoplastic adhesive applicators are manual, even applicators that are automated present problems. For example, while automated thermoplastic adhesive applicators are more efficient than the box applicator described above, they are also more expensive. The previously known automated methods dispose of the need to manually advance the carrier release tape, but are one-of-a-kind units and thus represent a very expensive option for both the adhesive manufacturer and the end user. Automated thermoplastic adhesive applicators are also limited to thermoplastic adhesive application to generally planar surfaces. In short, their limitations are similar to those of the previously known embodiments presented above because, due to their size, they may not be positioned for the application of thermoplastic adhesive into recessed areas or onto generally non-flat surfaces.
Thus, it will be appreciated that previously known apparatuses and methods have only contemplated use of the thermoplastic adhesive laden carrier release tape taught in the '670 Patent and the '442 Patent. The drawbacks of the previously known adhesive segments and methods of applying the same have been used in the industry without any marked improvement to date. In short, the application of adhesive segments from the carrier release tape remains inefficient, overly expensive, and generally inadequate for the application of adhesive segments to non-flat, recessed, difficult to reach, or unstable surfaces.
It is accordingly the primary objective of the present invention that it provide a handheld mechanical adhesive segment applicator apparatus capable of dispensing adhesive segments from an adhesive segment-laden carrier release tape. It is a related objective of the present invention that the handheld mechanical adhesive segment applicator apparatus have a drive mechanism for engaging an indexing instrumentality on the adhesive segment-laden carrier release tape to allow it to dispense adhesive segments.
It is another objective of the present invention that the handheld mechanical adhesive segment applicator apparatus be adaptable to apply adhesive segments to non-flat, recessed, difficult to reach, or unstable surfaces. It is a further objective of the present invention that it provide for the application of adhesive segments in a simple, efficient, safe, and automatic manner.
The handheld mechanical adhesive segment applicator apparatus of the present invention must also be of construction which is both durable and long lasting, and it should also require little or no maintenance to be provided by the user throughout its operating lifetime. In order to enhance the market appeal of the handheld mechanical adhesive segment applicator apparatus of the present invention, it should also be of inexpensive construction to thereby afford it the broadest possible market. Finally, it is also an objective that all of the aforesaid advantages and objectives of the handheld mechanical adhesive segment applicator apparatus of the present invention be achieved without incurring any substantial relative disadvantage.